I mean more in terms of being one of the quickest ways to get a functional AI that looks the way you want in front of people. Styling trends may butt up against usability but it's not as though using native code would have protected us from that -- look at Metro, for instance.

10MB might be a lot relative to what's going on (hard to think of many comparable applications that are as old as Gmail to me) but it's still a blip for most people's connections and certainly less trouble than using an installer.